Mats and Microbialites from Laguna La Brava

The Salar de Atacama depression is a unique geomorphologic structure in northern Chile and is the oldest and largest evaporitic basin in that country. In the lowest region of the Atacama basin, groundwater surfaces forms a series of lakes that are exposed to the extreme conditions of the salar, including high ultraviolet radiation, low humidity, high water-column conductivity, and arsenic concentrations. Among these lakes, Laguna La Brava harbors a variety of living microbialites and microbial mats. Several studies have determined the microbial diversity and the genomic basis of the main metabolic pathways that allow these microbial ecosystems to thrive in such extreme conditions, which resemble Precambrian/Paleoproterozoic conditions. This chapter reviews the results published since these unusual ecosystems were first described 4 years ago.